Roof supports for mine workings



1958 A. w. DUNCAN ROOF SUPPORTS FOR MINE WORKINGS 3 Sheets-Sheet 1 Filed Dec. 20, 1956 Lllllll 1958 A. w. DUNCAN ROOF SUPPORTS FOR MINE WORKINGS Filed Dec. 20, 1956 3 Sheets-Sheet 2 Nov. 25, 1958 Filed D60. 20, 1956 A. W. DUNCAN ROOF SUPPORTS FOR MINE WORKINGS 3 Sheets-Sheet 3 United States Patent ROOF SUPPORTS FOR MINE WORKINGS Angus Wellesley Duncan, Leigh Sintn, near Malvern, England, assignor to The Mining Engineering Company Limited, Worcester, England, a British company Application December 20, 1956, Serial No. 629,685

Claims priority, application Great Britain December 23, 1955 Claims. (CI. 6145) This invention relates to improvements in roof supports for mine workings.

All forms of roof support hitherto known incorporate some form of strut or pillar and they have to be relieved of their load before they can be moved forwardly into fresh positions to follow up the removal of the coal or other mineral. Various systems have been proposed employing telescopic hydraulic struts or pillars with hydraulic jacks or the like for advancing them, but such systems are expensive.

According to the invention means for supporting the roof of a mine working from the floor comprises in its simplest form two or more superimposed resilient or deformable cylinders or other members of circular crosssection adapted to roll upon each other and upon the surfaces of the roof and floor with which the top and bottom cylinders are in engagement when the support is in position so that the roof is supported by direct transmission of the load diametrically through the cylinders.

Any convenient means can be employed for locating the cylinders with their axes in a common vertical plane but the locating means does not take any part of the load and its only function is to maintain the cylinders in alignment.

Under load the cylinders will deform to a certain extent so that they will provide a substantial area of contact with the roof and floor.

As the cylinders can roll upon each other and upon the roof and floor of the working the support can be shifted horizontally under load by the application of a relatively small force, but preferably the cylinders are so arranged that the support can be off-loaded or the load can be reduced to a substantial extent to facilitate moving of the support from one position to another as work proceeds.

For this purpose the cylinders are conveniently formed as hollow shells of flexible but substantially inextensible material and are filled with a liquid such as water, means being provided for varying or controlling the volume and pressure of the liquid in the cylinders.

Each cylinder may, for example, be in the form of a rubber and fabric tyre mounted on a hollow hub or shaft rotatable in a framework in which it is guided for limited vertical movement. The tyre may be reinforced by steel wires incorporated in the walls and tread. V r

In one convenient practical construction a support comprises s'uperimposed hollow cylinders or tyres located relative to each other in such a manner that they'can rotate and also move vertically, the cylinders or-tyres being connected through running connections and flexible pipes or the like to means for controlling the volume and pressure of the liquid in the cylinders or tyres.

A unit will usually consist-of two spaced pairs of superimposed tyres mounted in a common framework which may also house an hydraulic accumulator and a reservoir to which the tyres are connected throughcontrelvalve ice In use the upper cylinder or tyre is in contact with the roof of a working and the lower is in contact with the floor and the liquid pressure in the cylinder is such in relation to the contact areas that the required support for the roof is provided. Any convergence of the roof and floor under a pressure exceeding the maximum normal loading of the support will deform the cylinders or tyres and cause liquid to pass into the hydraulic accumulator, thus storing energy.

To withdraw and reset the support the accumulator can be isolated by a manually operated valve and a pump can be operated to transfer liquid from the cylinders or tyres to the accumulator and reduce the loading on the support which can then be rolled forward into its new position. Thevalve is then opened and the accumulator restores the pressure in the cylinders or tyres to take the load. 7

The tyres being substantially inextensible the amount of liquid which has to be transferred to load and off-load the support is relatively small. Further, as the off-loading is progressive and under the control of the operator safety is ensured with a following roof.

As the support is off-loaded during moving it can be moved with relatively little elfort, the tyres rolling on each other and on the floor and roof. Further, unevenness of the roof or floor will not put excessive distorting loads on the bearings of the hubs or shafts on which the tyres are mounted and the surfaces of the tyres are not liable to be cut or otherwise damaged.

Any convenient method of moving the support may be employed and in a unit comprising two pairs of superimposed cylinders or tyres there may be independent hand travelling gear for each pair of cylinders or tyres for steering if the direction in which the unit is to be moved is not exactly at right angles to the axes of the cylinders or tyres.

A practical embodiment of the invention is illustrated by way of example in the accompanying drawings, in which:

Figure 1 is a side elevation of a support embodying two pairs of superimposed cylinders mounted in a rigid frame incorporating means for controlling the pressure in the cylinders, this view being taken in the direction of the arrows 11 in Figure 2.

Figure 2 is a front elevation of the support in part section.

Figure 3 is a horizontal-section on the line 33 of Figure 2.

Figure 4 is a schematic view showing the interconnection of the tyres, hydraulic accumulator, reservoir, and,

controls.

In the support illustrated there are two pairs of superimposed cylinders 10 mounted in a rigid rectangular frame 11 built up .from steel angle and channel section members bolted or welted together.-

The bottom of the frame is formed by a skid pan 12 which has openings in it through which the lower cylinders project and has an upwardly inclined peripheral flange 13.

Each of the cylinders 10 has the form of a rubber and fabric tyre of the cross-section shown in Figure 2, the wall of the tyre being reinforced with steel wires and being substantially inextensible. Each tyre is mounted on a flanged rim 14, and in the case of the upper tyre of each pair the rim is bolted to a flange on a sleeve 15 keyed on a hollow shaft 16 which is common to both upper tyres. The ends of the shaft are guided for vertical movement between pairs of parallel vertical anglesection members 17 of the frame, and the outer ends of the shaft carry worm-wheels 18 meshing with worms 19 which can be rotated by means'of handlesapplied to the squared ends of the worm shafts for rotating the shaft I6 and tyres 10. i i

The lower tyre 10 of each pair is mounted on a rim 2 l c arried, by anassembly 22-mounted on ball bearings 23;.ona, sha ft 24 .which its-common to both lower tyres. The. e'nds of the shaft are guided for vertical movement between the lower parts of the members 17.

The hollow. shafts communicate with the interiors of the tyres and the shafts are connected by running connections to a rese'rvoir and to an hydraulic accumulator mounted'in the frame between the pairs of tyres.

Thelayoutof the hydraulic system is shown diagrammatically in Figure 4.

All'four tyres are connected together by a pipe-line which' 'is connectedthrough a spring-loaded valve 31 toijan' hydraulicaceumulator32 containing a liquid, prefe'rably water, abova piston 33, the capacity of the accumulator'lbfeinga't least'equalto the total reduction of ih'cfvblufrie of 'thei'liquid. in the tyres .under full' deflection. "The spa-c634 "below the piston contains corripressedair whichisintroducedthrough a valve 35 from anyfco'rivriient sourcei "The accumulator is also connected through a pressure relief valveji36 to a pipe-line 37 of which one end is takento a reservoir 38 and the other end is connected through a valve 39 to a pipe-line 40 which is also directly connected through a valve 41 to the accumulator. The pipe-line 40 is connected to the smaller or high pressure end ofa difierential piston and cylinder assembly 42 and through a valve143 to the main pipe-line 34). The larger or lovv pressure end of the differential piston and cylinder assembly 42 is connected through a non-return valve 46 to the reseryoir and through a valve 44 to the main pipe-line SQ Which is also connected through a valve 45 to the reservoir The pressure 'in the tyres under any given conditions is indicated by a pressure gauge 47 in the pipe-lineal.

The, system, including the tyres, reservoir and accumulator is initially filled with water or other liquid in any conventionalmanner and the accumulator is charged with air or other suitable gasundenpres'sure through valve35. i V i To set the support after it has been located in position in a workingfposition valves 41 and 44' are'opened valves 39, 43'and '45 being closed, Liquid from the ac'cumulator is forced into the smaller or high pressure end ofthe difierential piston and cylinder assembly to raise the piston and force liquid at lowpressure from, the larger endof the assembly through the valve'44 into the tyreslto charge these at low pressure.. Valve 44is then closed andvalve43 isopened to apply the'full accuculator, pressure to the tyres. Valves 41 and 43 are then closed.

In the normal standing condition of the supo'rt'u'nder load valves 41, 43, 4'4 and 45 are closedand valve 39 is open. The tyres are connected through the springloaded valve 31 to the accumulator which is also connected through the pressure relief valve 36 to the reservoir. The reservoir is connected to both ends of the differential piston. and cylinder assembly which are kept full of liquid.

'To relieve the, pressurein the tyres it is only necessary to open valve 45 which connects the tyres tothe reseryou.

'The support is thus off-loaded and can be readily moved to afresh position with a minimum of effort.

To reset the supportjn its fresh position valves 39 and 45 are closed andvalves 41 and 44 are opened to allow liquid" from the accumulator to. enter the small. end' of the differential piston1and 'cylinder assembly and raise the piston which forces liquidfrom the larger end of the cylinder into the tyres.

To preload'the support valve 44 is closedand valve 43 is opened to admit liquid at accumulator 'p'ressiire to the tyres..

If," owing to approaching of the roof and floor, the

. pressure in the tyres increases beyond a predetermined majriinurn the relief valve 31 opens and 'liquidi's di'splaced from the tyres into the accumulator.

If the pressure produced in the accumulator exceeds a predetermined maximum value which is controlled by the loading of the relief valve 36 that valve opens and allows some. liquid to. pass from the accumulatorinto the reservoir.

The hydraulic layout described above is entirely automatic as 'it leaves the tyres free to discharge to thereservoir if necessary during moving, and the unit is reset to the load sustaining capaicty equivalent to the. accumulator pressure.

It will be appreciated however, that simpler means for controlling the pressure in the tyres can be employed if it is desired to reduce the cost of the unit.

In the simplest form a blow-oh valve connects the tyres to. a tankorreservoir mounted in, the framework and maintained at or only slightly-above.atmospherie pressure. To ofl-load the unitfor moving, a manually controlled-valveallows liquid tofiow from the tyres-into, the reservoir. To reset the unit after moving, is pumped from the reservoir intothe tyres by means ot a hand pump.

This arrangement is simple and economical but are, quires time, and manual'effort for operation and it ha s the disadvantage that the final setting pressurev for the tyresiscontrolled by the operator.

In another form the tyres areconnectedthrough. a blow-nit valve to an hydraulic accumulator having a maximum working pressure just below the minimum tyre pressure under load.

Tooft-load, liquid is pumped from the tyres into the accumulator, andto reset the unit'aft'er moving, the ac cumulatoris connected to the tyres through a rna'nually operated valve which by passesthe .blowY-ofi valve.

This arrangement has the advantage. that the unit is set to a predeterminedpressure, but it reqniresti meand manual efiort for off-loading. Further, iijbroken door or roof has to. bev negotiated in movingl the unit'forward turther pumping to ofi-load may b'e necessary as a predes termined volume of liquid is trappedinthe tyresduri ng moving i i v I i Movement of the support illustrated is efiected by ro.-. tation of the uppertyres by meaiis ofthew rmsIIQ. If it is desired to be ableto steer;thesupportwherinroving it the two. upper tyres rn ay be mounted. on. separate shafts, "so that the suppert can beisteered in any desired direction by 'difi'e'rential' rotation of. the. shafts and, tyres. WHenIthe support of the invention-is inhondoadledc'ondition' of the tyres, are. nor'nprssuriz'ed thersup'port will be retained'in a v'ertical'br substantially 'vert ical posi: tionnby engagement of the. pan .12 or ,its flange, 13' with the'ground." i

It will be appreciated. that various other methods of moving the 'supportni'ay be employed. It may, for ex: ample, simply be pushed or, pulled to its new position after cit-loading. Alternatii/iely, the. support may be moved by applying .a. tangential force. tothe periphery of one or thereof the; tyres: to.cause them to rotate. For thisnpnrposea flexible .band may be carried through be: tw'e'e'n'a pairof tyres which are rotatedby pulling ph one end of the band, or rotatable rollers may be mounted in the frame for frictional engagement withone or more of the tyres.

The supportcan be; broken up into a'number, of reasonably light ,and easily handled-components which. facili-I tates itsv transport. to theworkingface in a;mine'.-and the components can berapidlyand easily assembled.

' Deformation of the tyres'under load will take-care-of minor variations in the seam height and'supports can be supplied with-tyres of various diameters. p

Itis not; of'c'ourse, essential that both of'the super ltn posed tyres in a support should be of the same-diameten:

I claim:

1. A roof support for underground workings comprising a plurality of superimposed rotatable members of circular cross section in rolling contact one upon the other and having their axes in a common plane whereby a load applied to the support is transmitted diametrically through said members, and frame means maintaining said rotatable members in a superimposed position.

2. A roof support for underground workings comprising a plurality of superimposed rotatable cylinders, and means for maintaining the axes of said cylinders in a common substantially vertical plane and permitting movement of the axes in said plane, said cylinders being in rolling contact with one another, so that a load applied to the support is transmitted diametrically through said cylinders.

3. A roof support for underground workings comprising a frame, a plurality of superimposed cylinders rotatably mounted in said frame in contact at all times one with the next and having their axes in a common substantially vertical planeand each guided for vertical movement in that plane, the surface of the uppermost cylinder extending above said frame and the surface of the lowermost cylinder extending below said frame.

4. A roof support for underground workings comprising a frame and at least one pair of superimposed cylinders of flexible and substantially inextensible material, means for filling said cylinders with a liquid at variable pressures, so as to vary the height of said support to conform with variations in roof-to-fioor height, the cylinders being rotatably mounted in said frame with their axes in a common substantially vertical plane and being guided for movement with respect to said frame in said plane, each cylinder being in rolling contact with that adjacent to it in a vertical direction.

5. A roof support for underground workings comprising a frame, parallel hollow shafts rotatably mounted in said frame with their axes in a common substantially vertical plane and guided for movement with respect to said frame in said plane, rims on said shafts, tyres made of flexible and substantially inextensible material mounted on said rims and filled with liquid, said tyres being in communication with said shafts, and means for controlling the volume and pressure of the liquid in said tyres, each of said tyres being in rolling contact with each tyre adjacent to it in a vertical plane.

6. A roof support for underground workings as in claim 5, wherein said support includes two pairs of superimposed liquid-filled tyres arranged side-by side with the axes of each pair of tyres in' the same vertical plane, the upper tyre of each pair being adapted to engage the roof 6 of the working when the support is in position and the lower tyre being adapted to engage the floor of the working, and the load carried by the support being transmitted diametrically through the tyres from the roof to the floor.

7. A roof support for underground workings as in claim 5, wherein an hydraulic accumulator, a reservoir, and a differential piston and cylinder assembly are located in said frame and are connected to the tyres through manually controlled valves providing the selective connection of the high pressure end of the differential piston and cylinder assembly to the accumulator and of the low pressure end to the tyres, and the isolation of the low pressure end from the tyres and the connection of the accumulator directly to the tyres.

8. A roof support for underground workings as in claim 5, including an accumulator and reservoir located in said frame, a spring-loaded valve for permitting liquid to pass from the tyres to the accumulator when the pressure in the tyres exceeds a predetermined value, and a second spring-loaded valve for permitting liquid to pass from the accumulator to the reservoir when the pressure in the accumulator exceeds another predetermined value,

9. A roof support for underground workings comprising a frame, two parallel hollow shafts rotatably mounted in said frame with their axes in a common substantially vertical plane and relatively movable in said plane, rims on said shafts, upper and lower tyres made of flexible and substantially inextensible material mounted on said rims and filled with liquid, said upper and lower tyres being in rolling contact with one another, said tyres being in communication with said hollow shafts, means for controlling the volume and pressure of the liquid in said tyres, and means for positively rotating at least one of said shafts for causing the upper tyre to roll on the roof of the working and on the lower tyre which rolls on the floor of the working to move the support laterally.

10. A roof support for underground workings, comprising a frame, a plurality of superimposed cylinders rotatably mounted in said frame and disposed one above another with their axes in a common vertical plane, each of said cylinders being in rolling contact with the adjacent cylinder, each of said cylinders being movable in said vertical plane, and means for positively rotating at least one of said cylinders.

References Cited in the file of this patent UNITED STATES PATENTS 

